Wrangler advises buyers not to wash the jeans unnecessarily, and after 15 days, to use a "reload spray" (sold separately) to give the fibers an ingredients boost for up to 67 to 95 additional wears.

LEG SAVERS

Other high-performance skincare ingredients, according to Wrangler, include apricot-kernel oil, passion-fruit oil, rosehip oil, and Shea butter, as well as monoi de Tahiti, a Polynesian ingredient made by soaking tiare flower buds in refined coconut oil.

After 15 days, Wrangler advises buyers to use a “reload spray” (sold separately) to give the fibers an ingredients boost.

Jagger, whose mother is famous American model Jerry Hall, describes the Denim Spa line as softer and smoother than conventional denim. “They definitely feel cooler than regular jeans,” she says in a promotional video. “After a day wearing them, my legs feel great—they come out feeling more silky than usual.”

The effect isn’t forever, however. Wrangler advises buyers not to wash the jeans unnecessarily, and after 15 days, to use a “reload spray” (sold separately) to give the fibers an ingredients boost for up to 67 to 95 additional wears.

The three models of jeans, which will be available online at ASOS come January, are expected to retail for £85, or $135. Snake oil or savior? Caveat emptor.